Volatile metabolites of Lecanicillium saksenae (Kushwaha) Kurihara and Sukarno and their toxicity to brinjal mealybug Coccidohystrix insolita (G)

Abstract

Lecanicillium saksenae (Kushwaha) Kurihara and Sukarno is a versatile indigenous entomopathogenic fungus with high speed of kill on hemipteran insects. Investigations were carried out to explore the volatile metabolites of L. saksenae and bioefficacy of its crude toxin to different life stages of brinjal mealybug, Coccidohystrix insolita. GCMS spectrum of crude toxin extracted from cultures grown in potato dextrose broth and Czapak Dox medium revealed the presence of 25 compounds each. The major secondary metabolites identified were 2,6 pyridine dicarboxylic acid (dipicolinic acid), n-hexadecanoic acid, octadecanoic acid, harmine, dl- mevalonic acid lactone, 2-piperidinone, 4H-pyran-4-one 2,3-dihydro-3,5dihydroxy-6methyl, acetamide,N-(2-phenylethyl), pyrrolo [1,2-a] pyrazine-1,4-dione, hexahydro. The biological properties of these compounds include insecticidal to nematicidal and antimicrobial activities. Bioefficacy studies with crude toxins revealed the toxicity of secondary metabolities to C. insolita. The dose dependent bioassay revealed 100 per cent moratality at a higher concentration of 1000 ppm at 72 and 96 h after treatment on nymphs and adults respectively. Results highlighted the role of secondary metabolites in the pathogenicity of saksenae and pave way to the utilization of its biocide molecules in safer pest management.